Bio2 Lecture 13

Bio2 Lecture 13 - Bio2 Lecture 13 3/1/05 Musculoskeletal...

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Bio2 Lecture 13 3/1/05 Musculoskeletal System Skeletal system - Supports and protect the body - In chordates, the endoskeleton, the muscles are attached to the bones, and they are the base for muscle action Types of Skeletons - Hydrostatic – example is the earthworm, hydrostatic skeleton is a fluid filled cavity, organism moves by the segments it has, it gets thin in one area and fat in another, one muscle group is causing it to contract and extend at various areas - Most efficient of the hydrostatic skeleton are earthworms, because of many segments - Exoskeleton, arthropods have it, beetles, crustaceans, it is a hard outside covering made of chitin - Disadvantages to organisms that have this is in order for them to grow, they have to shed the exoskeleton, while they are shedding their exoskeleton, they are exposed, no longer protected by hard exoskeleton - Endoskeleton - Humans have endoskeleton, chordates all do, but echinoderms also have an endoskeleton How it muscle works - Works in an antagonistic way, when you flex, your biceps are contracting, antagonistic muscle is the tricep, which is relaxing, when you extend it’s the opposite, the biceps are relaxing, and the triceps are contracting - Muscles are only able to contract, and muscles also work in pairs - Muscles are connected to bones by tendons, tendons are a connective tissue, and muscles need this so they move the bone when they contract - Epimysium, the outside connective tissue, and muscle you can also pull apart like string cheese, each individual rod or string is a fasicle , within each fasicle you have the muscle fibers, and its surrounded by connective tissue called perimysium - Each muscle fiber is a complex cell, it is a striated muscle and multinucleated o T tubule are tubes that wrap around the myofibril above the sarcoplasmic reticulum and come out paramycium o Has many nuclei o Also has many mitochondria, they supply muscle with energy
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Bio2 Lecture 13 - Bio2 Lecture 13 3/1/05 Musculoskeletal...

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